1. Field of the Invention
The present invention relates to an image processing apparatus capable of color conversion of color image data to achieve faithful reproduction in an image recording device, and a method therefor.
2. Related Background Art
In case of printing texts, computer graphics or images, prepared by an operator in an application task on host equipment, by a recording device such as an ink jet printer, various methods have been devised for exactly reproducing on the recording device the color desired by the operator.
In certain systems there is employed, for example, a method of setting profile data is employed representing the characteristics of input and output devices, corresponding to the input and output devices of the system and converting the R, G and B values defined in the color space of the input device into the C, M, Y and K values of the color space of the output device by reading thus set profiles of the input and output devices, thereby reproducing the color, desired by the operator on the input device, exactly on the output device, or returning these values to the R, G and B values of the color space of the input device for preview on a monitor.
In such method, however, only one profile can be selected for each input or output device. However, for example, in a binary recording device in which recording is determined by forming or not forming each dot, as in the ink jet recording device, the color reproduction range or the output rendition characteristics may even vary for the same output device, by the binarizing method for the image data containing tonal rendition, such as the dither method or the error diffusion method. Besides such variation in the color reproduction range or the output rendition characteristics may occur even for the same binarizing method on a different recording medium such as coated paper and plain paper. Furthermore, in case of faithfully reproducing the image, displayed on the monitor, in the recording device, even the image on the same monitor may vary by the adjustable values thereof such as the gamma value and the white point. Consequently, even when the input and output devices are fixed, the exact reproduction of the desired color cannot be achieved by a set of profile data if there is a variation in the binarizing method, recording medium or adjustable values.
Also in certain applications, there is conventionally adopted a method of registering in advance colors reproducible on a specified recording device by the mixing ratios of elementary colors, for example C=20%, M=50%, Y=30% and K=0% for a sample color No. 1, and effecting designation of a color by the number of such sample color while referring to the sample colors printed in advance by the specified recording device.
In such method, however, the color samples only contain the C, M, Y and K values while exact colors are not reproduced on the monitor of the host equipment where the operator works.